Data processing installations of moderate to major capability generally are situated within the internal regions of buildings which have been designed to provide not only rigidly controlled environments through dedicated air-conditioning systems and the like, but also accurately regulated and reliable supplies of power. In the latter regard, line power now available from utilities for use by the computer facilities has been observed to be deteriorating in quality to the extent that, for the most part, it has become unacceptable for direct application to data processing systems. Vagaries in line power stem from many causes but are categorized principally as line transient and out-of-specification voltage. Line transient may develop from a variety of perturbations, for example they may be generated due to short circuits along the distribution lines, utility primary switching, radio frequency interference, lightning or power factor corrections manifested as oscillatory ringing transients. Under-voltage or over-voltage phenomena generally occur in conjunction with regulator activity, load changing on the power line, short circuits and lightning.
When imposed upon computer operations, line transients are characterized by data errors, unprogrammed jumps and software/data file alterations. Momentary under-and over-voltage phenomena can result in automatic computer power down and, in extreme cases, damage to the equipment.
To overcome the aberrations of line power supplies, a variety of power conditioning devices have been installed within the computer room facility. For example, uninterruptable power supplies (UPS) using a battery charger, batteries, an inverter, and static switch arrangement may be installed to evoke waveform recreation, or motor generators may be provided. In some approaches, systems which modify, but do not recreate, waveforms such as voltage regulators or spike suppressors are utilized. These latter systems basically are ineffective in the treatment of all line conditions which may be encountered. Regulators, for example, incorporate feedback loops, the performance of which is too slow to render the devices effective in computer applications. UPS systems when configured for reliable performance, are effective but heretofore have been found to represent a significant capital investment.
Recently, a polyphase, ferroresonant voltage stabilizer or synthesizer has been successfully introduced to the marketplace. In their elementary form, such synthesizers comprise a regulator which is fashioned as a non-linear saturable transformer arrangement in parallel with a capacitor assemblage which is supplied from the line source through an input inductor. The saturable transformer components and capacitors form a ferroresonant circuit wherein the reactive components operate beyond the knee of a conventional magnetization curve. Described in U.S. Pat. No. 4,305,033 by Jeffrey M. Powell, the noted ferroresonant voltage stabilizer or synthesizer enjoys advantages of economic construction and efficient performance while remaining immune from certain unsatisfactory characteristics related to stability and reliability which previously had been associated with resonating circuits. Literature concerning this ferroresonant approach to power conditioning has been generated as is evidenced by the following papers:
I. Practical Equivalent Circuits for Electromagnetic Devices by Biega, The Electronic Engineer, June, 1967. PA1 II. Static-Magnetic Regulators--A Cure for Power Line "Spikes" by Kimball, Electronic Products, reprinted by Thomas and Skinner, Inc., Bulletin No. L-552. PA1 III. A New Feedback-Controlled Ferroresonant Regulator Employing a Unique Magnetic Component, Hart, IEEE Transaction on Magnetics, Vol. MAG-7 No. 3, September, 1971, pp 571-574. PA1 IV. A Feedback-Controlled Ferroresonant Voltage Regulator, Kakalec, IEEE Transactions on Magnetics, Vol. Mag-6, No. 1, March, 1970. PA1 V. Design Techniques for Ferroresonant Transformers by Workman, Jr. reprinted by Thomas and Skinner, Inc., Bulletin No. L-551. PA1 VI. Comparison of Inverter Circuits for Use in Fixed Frequency Uninterruptable Power Supplies by Bratton and Powell, Instrument Society of America, ISA-76, International Conference and Exhibit, October 11-14, 1976.
For any approach taken with respect to the conditioning of line power for computer room purposes, power losses will be experienced which are manifested in the form of heat which is released to the computer room environment. As a consequence, the air-conditioning system dedicated to that computer room environment must not only accommodate the requirements of the computer system, but also the loss generated heat occasioned by power consumption. In assessing anticipated costs, the computer facility owner also must evaluate the cost associated with the loss in power due to the efficiency level of the power conditioning system and the corresponding cost occasioned by the power required to remove heat generated in consequence of lower efficiences. For principal computer room installations, these costs can be significant.
Experience has shown that the above-discussed ferroresonant power conditioner devices exhibit efficiencies of about 91% which are considered to be excellent. Correspondingly, UPS systems have been observed to exhibit efficiencies of about 85%. Where for example, 100 KW computer facility installations are involved, the efficiency associated with a UPS system may impose power costs of about $10,000.00 for a year's operation at about six cents per kilowatt hour. Of course, in regions of higher rates, for example, about 15 cents per kilowatt hour, such power cost will amount to about $23,000.00. It follows that improvements in efficiency of, for example, a single percentage point, will represent significant cost savings to the computer facility operator.
Another aspect of efficiency level performance resides in the costs associated with the fabrication of power conditioning equipment. For example, where higher levels of efficiency are achieved in inductive device performance or in conjunction with reactor operation, then the components themselves may be fabricated at lower and less costly scale.